Men who have sex with men (MSM) in the US are most heavily affected by HIV, representing ~63% of all new HIV infections annually. With highly effective HIV medication and consistent engagement in HIV health care, these MSM are living longer; by 2015 it is estimated that more than 50% of Americans living with HIV will be 50 years of age or older. Evidence is emerging that chronic pain is prevalent in older HIV-infected patients and likely occurs synergistically with substance use and abuse, which predispose to non-engagement and non-retention in HIV care, non-adherence to HIV medications and sexual risk taking. Understanding these relationships and incorporating pain management strategies in health interventions will forge the development of a tailored behavioral-based, integrated intervention that has the potential to improve pain management, reduce substance use (and/or its interference in HIV disease management) and improve ART adherence and engagement in care Design. The aims of this application are to: (1) characterize chronic pain and substance use/abuse in older HIV-infected MSM, through patient generated themes extracted from qualitative interviews; (2) identify significant direct and mediated relationships between chronic pain, substance use, HIV medication adherence and sexual risk-taking, assessed via a quantitative comprehensive assessment battery; and, (3) determine the feasibility and acceptability of a group-level, integrated behavioral intervention to address chronic pain and substance abuse that could increase engagement in care and HIV medication adherence and decrease sexual risk taking, through an open pilot. We will also assess the potential for an effect examining pre-post differences on pain, substance use, HIV treatment, and sexual risk outcomes. To achieve these aims, self-generated emerging qualitative themes from 20 in-depth interviews will inform the development of a comprehensive, specifically tailored quantitative health assessment for 60 older HIV-infected MSM. The cross-sectional qualitative and quantitative data will specify a novel group-level, intervention to be piloted with 30 participants (6 groups of 5 men). These results will set the stage for a R34 RCT application to estimate controlled treatment effect sizes. This application is the first known attempt to investigate the behavioral processes involved in the association of chronic pain with substance use/abuse, engagement in care, HIV medication adherence and sexual risk taking among older MSM living with HIV. Furthermore, this is the first attempt to develop a group- level, integrated intervention specifically tailored to older HIV-infected MSM, an at-risk group who are disproportionately represented with HIV. These findings have the potential to change chronic pain and substance abuse treatment paradigms for older HIV-infected MSM and could improve engagement in care and decrease sexual risk taking.